Mechanisms of respiration and phosphorylation in Ascaris muscle mitochondria

In Ascaris muscle mitochondria the major respiratory chain-linked phosphorylation activity is accomplished by a NADH-linked reduction of fumarate to succinate. Oxygen can also be employed as a terminal electron acceptor via a cyanide- and salicyl-hydroxamate-resistant terminal oxidase. As in fumarate-dependent electron transport this process appears to be coupled to energy conservation at phosphorylation site I. The branchpoint from which electrons are taken from the main respiratory chain to either the alternative oxidase or fumarate reductase is likely to be on the oxygen side of the NADH dehydrogenase segment.Malate and succinate are the only substrates which appreciably support respiration in the mitochondrion of the nematode. Regardless of the presence or absence of oxygen malate is utilized by an oxidation-reduction reaction resulting in the formation of pyruvate, acetate, succinate, propionate and CO₂. In addition, aerobically, hydrogen peroxide is formed as the product of oxygen reduction. Succinate accumulation was found to be significantly higher in the anaerobic as compared to the aerobic incubation mixtures. This effect was accompanied by an increase in anaerobic malate consumption. ATP generation and the formation of pyruvate, acetate and propionate were found to be similar in the presence and absence of oxygen.In malate-supported respiration of intact Ascaris mitochondria reducing equivalents (NADH) are produced exclusively through pyruvate and acetate formation. These enzymatic reactions are functionally coupled to the electron transport-linked reductions of fumarate to succinate and oxygen to hydrogen peroxide, respectively. In accordance with the position of the redox potentials of the fumarate/succinate and O₂/H₂O₂ couples, anaerobic and aerobic respiration was found to be associated with relatively low energy conservation efficiencies. Thus one molecule of ATP was conserved per 2e^? transferred to fumarate or oxygen, respectively. No evidence could be obtained for a significant activity of energy conservation sites II and III and electron transfer through the alternative oxidase pathway was shown not to be coupled to phosphorylation.     

Small vessel vasculitis caused by hepatitis B virus immune complexes: Small vessel vasculitis and HBsAg

In a comprehensive study of 80 patients with vasculitis, 4 had concurrent hepatitis B virus (HBV) infection. Polyarteritis nodosa was present in 2 and in the other 2, cutaneous vasculitis, presenting clinically as palpable or Henoch-Schönlein purpura. In one of these patients skin biopsies demonstrated granular deposits of IgM, C3, C4, and the hepatitis B surface antigen (HBsAg) and electron-dense deposits of aggregated 20-nm particles resembling HBsAg in postcapillary venules. Evidence for circulating HBsAg-immune complexes included increased serum C1q binding activity, decreased serum complement, and a cryoprecipitate containing both HBsAg and IgM anti-HBs. Aggregated 20-nm particles resembling intact HBsAg were also seen by negative staining electron microscopy of the serum cryoprecipitate. This patient fulfills all the criteria for a specific immune complex vasculitis caused by his immune response to a chronic HBV infection. These findings emphasize that HBV infection may be associated with small vessel vasculitis as well as polyarteritis nodosa, mixed cryoglobulinemia, and glomerulonephritis. A similar immune response to other viral infections may be expressed as palpable (Henoch-Schönlein) purpura also.     

Tonic heart rate level, social class and antisocial behaviour in adolescents

On the basis of previous empirical research it was hypothesised that (a) antisocial behaviour in adolescence would be characterised by lower tonic heart rate levels and (b) any such relationship would be particularly borne out in the higher social classes where the 'social push' towards antisociality may be relatively weaker. These predictions were tested by relating tonic heart rate levels in a sample of 15 year old male schoolchildren to self-report and teacher ratings of antisocial behaviour/undersocialization. An 'antisocial' group was found to have significantly lower heart rate levels than a 'prosocial' group. Several analyses on high and low class groups resulted in a significant low heart rate/antisociality relationship in the high classes only. It was speculated that the heart rate/antisociality relationship may be mediated by somatotype, or alternatively that low levels in high class antisocials may reflect a vagal passive adaptation to mildly aversive events.     

Polymyositis: Essential Information for Primary Care Providers

Polymyositis is one of a rare group of skeletal muscle diseases known as idiopathic inflammatory myopathies. The etiology is not fully understood, and its clinical presentation is often vague yet similar to more common neuromuscular diseases, making diagnosis difficult. A number of different tests are available to assist providers in making an accurate diagnosis. Once a diagnosis is made, there are a number of various treatment modalities available. Nurse practitioners must be familiar with treatment protocols and follow-up. The focus of this article is on polymyositis; its presentation, signs, and symptoms; the process of accurate diagnosis; and common treatment strategies.     

Detection of ischemic myocardium in vivo through the chest wall by quantitative ultrasonic tissue characterization

Quantitative analysis of ultrasound offers a potentially valuable method for noninvasive differentiation of specific types of cardiac disease and for assessment of their severity. Clinical application necessitates quantitative measurement of the ultrasonic properties of myocardium through the chest wall. This study was designed to determine whether such measurements could be made noninvasively with the aid of conventional M mode echocardiographic guidance and to characterize the quantitative effects of intervening tissue (chest wall) on the ultrasonic signals backscattered by ischemic and normal myocardium. Frequency-dependent ultrasonic backscatter (2 to 7 MHz) from normal myocardium was measured in dogs in vivo through the closed chest with the use of M mode guidance and with the chest open, directly from the myocardium. Closed-chest and open-chest measurements were repeated after ligation of the left anterior descending coronary artery in the same animals. Closed-chest data were compensated by correcting for the average value for the slope of the attenuation-frequency function of chest wall, which was determined from measurements obtained by analysis on excised tissue. Compensated closed-chest measurements correlated with measurements obtained from the epicardial surface of the heart. The differentiation of normal from ischemic myocardium with both the closed- and open-chest measurements was consistent (p < 0.005). The successful differentiation of normal from ischemic myocardium by determination of quantitative backscatter through the intervening chest wall supports the concept that tissue characterization by quantitative analysis of backscattered ultrasound is a potentially useful, clinically applicable approach to noninvasive detection and differentiation of intrinsic properties of normal and diseased myocardium.